Protecting device for induction-motors.



"0.703302. Patented luly I, I902. J. H. mama.

PROTECTING DEVlOE FOR INDUCTION MOTORS.

Applicatiun Med Oct. 21, 1901.) 'No Model.)

W/ TNE SSE S IN VF N T 0/? 3.. r Q/WF 4 9 A TTOHN E Y UNITED STATES PATENT OFFICE.

JOHN HENRY DIGGLE, OF LASALLIJ, ILLINOIS.

PROTECTING DEVICE FOR INDUCTION-MOTORS.

SPECIFICATION forming part of Letters Patent No. 703,902, dated July 1, 190.2.

Application filed October 21,1901. Serial No. 79,444- (No model.)

To all whom itmcty concern.-

Be it known that I, JOHN HENRY DIGGLE, a citizen of the United States, residing at La salle, in the county of Lasalle and State of Illinois, have invented certain new and use- :ful Improvements in Protecting Devices for Induction-Motors, and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention pertains to induction-motors; and it has for its object, primarily, to provide a simple and cheap yet most efficient and effective and durable protecting device for an indnction-motor,particularly for threephase induction -1notors. Ordinarily these motors require a starting-current of from four to six times f ull-load current until they attain full speed. Usually as installed these motors are connected to the line by means of a switch and fuse-block. In order to start the motor, the fuse in the fuse-block has to be strong enough to carry from four to six times full-load current for a short time-say a few minutes, or until the motor has reached full speed-and it will therefore be readily seen that such a fuse affords practically no protection to the motor from heavy overloads.

My present invention, therefore, has for its object, among others,to provide means whereby the motor may be started either with a heavy fuse or its equivalent having a carrying capacity equal to that required for the starting-current, and when the motor has acquired full speed to cut this fuse out of the circuit, and the current thus allowed to travel through a smaller fuse sufficient to prevent or protect the motor from overloads or heavy rushes of current.

Other objects and advantages of theinvention will hereinafter appear, and the novel features thereof will be specifically defined by the appended claims.

The invention in its preferred form is clearly illustratedin the accompanying; drawings, which, with the numerals of reference marked thereon, form apart of this specification, and in which- Figure 1 is a front elevation of a switchboard, showing my improvements. is a side-elevation thereof.

Like numerals of reference indicate like parts in the different views.

Referring to the details of the drawings, 1 designates the switchboard, provided with an insulating-base 2. 3, 4, and 5 are the terminals secured to said base, and 6 designates the light fuses disposed between the poles of the switch, as is clearly shown in the drawings. The fuses in this instance are shown as inclosed fuses, secured to the terminals by means of screws 7; but it is evident that any other suitable form of fastening-s may be employed; also, the fuses can be almost any style, either open or inclosed, as may be found most expedient.

8 designates the heavy fuses, which may be made of any material suited to the purpose, shown in this instance as being the switchblades, pivotally mounted, as at S), and provided with a suitable handle 10. \Vhen the switch is closed, these heavy fuses or switchblades, which in some instances I make of copper, are designed to carry the bulk of the current until the motor has acquired full speed,when the switch is opened and the light fuses will carry the current.

From the foregoing description when taken in connection with the annexed drawings the operation and advantages of my invention will be readily understood. It will effect a saving in the wear of the motor, it will not add materially to the cost, and its numerous advantages will be manifest to those familiar with this class of devices.

The base or switchboard is shown as pro vided with suitable openings for the passage Fig. 2

of the screws or other means that maybe employed to secure the switch in any desired place in any position required.

The size and shape of the switchboard may be varied as occasion may require. Neither is the present invention confined to the application thereof to a three-phase motor.

From the above it will be evident that I have devised a simple and cheap novel form of switchboard and protecting device for inductionunotors, and while the structural embodiment of the invention as herein disclosed is what I at the present time consider the preferable one it is evident that changes, variations, and modifications may be resorted to Without departing from the spirit of the invention or sacrificing any of its advantages, and I therefore do not Wish to restrict myself to the details of construction hereinbefore described and as shown in the accompanying drawings, but reserve the right to make such changes,variations,and modifications as come properly within the scope of the protection prayed.

What is claimed as new is 1. A protecting device for induction-motors, comprising fuses connected with the terminals of the switchboard, and pivoted independent fuses and a handle carrying the JOHN HENRY DIGGLE.

tVitnesses:

E. \V. SAMEN, HENRY U. N 101101;. 

